Fire suppression systems using aqueous film forming foam (AFFF) solutions are often installed in facilities containing flammable or combustible liquids because of the rapid and efficient fire extinguishing capability of such foams.
Although various types of fire fighting foams are available, AFFF is used almost exclusively because of its superior fire extinguishing capacity. AFFF formulations contain a class of chemicals known as perfluorinated compounds (PFC). Examples of PFCs include perfluorooctanesulfonic (PFOS) and perfluorooctanoic acid (PFOA). PFCs are very stable chemicals that do not change or break down in the environment, or in vivo. As a result, residues of these compounds may accumulate in soil, sediments, water or food chains. When spilled or disposed of, PFC's can enter groundwater and be transported, potentially affecting nearby water supplies.
All the constituents resulting from fire fighting exercises are considered to have adverse environmental effects. The organic constituents in AFFFs have been reported to resist biodegradation in conventional biological processes as well as contributing to operational problems. Industrial wastewater has also been implicated as a likely source of entry of PFOS and PFOA into natural waters thereby entering domestic water. Research efforts have therefore been directed towards developing a remediation method for treating AFFF wastewater containing PFCs.
Naturally occurring materials have found many applications as sorbents. However the effectiveness of such materials for the removal of contaminants can be greatly improved by tailoring a sorbent to sorption of a particular compound or class of compounds. Application of tailored materials offers several advantages including low cost of natural materials, versatility in the preparation of selective and modified materials for target contaminants and abundant availability.
As such, a need exists for sorbents which are suitable for the sorption of hydrophobic organic contaminants such as constituents of AFFFs, surfactants and/or perfluorinated compounds.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.